Pressure controlling appliance



Nov. 11, 1952 A. CARTER y ET AL v 2,617,645 PRESSURE CONTROLLING APPLIANCE Filed July 6, 1949 y Patented Nov. 11, L1952 UNlrED s s'rmi'ss4 PATmVrori-lcs "`"'Artl1ur Carter, Halesowen, near Birmingham, and George Slade, Oldbury,"l England; said Slade assignorto said Carter Appiicatin july, 6, 1949, seal No. 103,272 Inoreat Britainmly s, 194s 1- ciaim. (c1. 2er-,1)-

This invention relates to pressure controlling or cushioning appliances applicable to presses vforthe drawing or cupping of sheet-metal articles from blanks in order to give'a controlled resisting pressure to the downward movement of the draw ring, but also being applicable generally for the purpose of offering a controlled resistance to a moving part; the said appliances being of the kind in which a hydraulic fluid is acted upon by a main ram or plunger in a primary cylinder and is forced through a resistance opening or passage into a secondary cylinder in order to act upon and depress a piston therein, said piston operating against a spring or other elastic Y' medium which returns the piston and displaced fluid when the applied force is relieved from the ram or main plunger.

The object of the present invention is to pro-r vide an applianc-e of the kind referred to, with a self-contained resistance and return-flow unit that can be placed anywhere in a pipe line connecting the primary cylinder to the secondary cylinder, so as to be readily accessible for repairs or the like. Y

The accompanying drawing is a part sectional view of a pressure controlling appliance in accordance with the invention.

Referring to said drawing, which showsan appliance. intended for cushioning the downwardv movement of the pressure or draw ring of a press, the usual pins depending from the said draw ring rest upon a pressure plate I supported uponl the upper end of a main ram 3 movable ver# tically in a primary cylinder 4. This primary cylinder 4 is connected by pipes 33, 34, to a sec-- ondary cylinder 8 containing a vertically-moving piston 9 supported upon a spring I9 adapted to resist downward movement of the piston 3 and to return the same toits normal raised position. A pump is provided for automatically returning any fluid which has leaked past either.

the primary or secondary pistons. This pump comprises a hollow plunger I2 depending from piston 9 and sliding in a stationary cylinder 23.

This cylinder has its upper portion of reducedr diameter and the plunger I2 is grooved intermediate its ends, at |21. The said plunger has a single passage 21 in it, controlled by a ball valve 28 and passing from the lower face of the plunger I2 to the hollow interior, which is open'v to the topface of the piston 9. An inlet valve 39 for the pump cylinder 23 is tted to a passage 29a in the bottom plate 45 closing the lower end of the cylinder. Any iluid leaking past piston 9 is received in the vessel 49 enclosing the pump,

ves-sel 49 is drawn into cylinder 23 through valve` 30a and on the down stroke uid is discharged through passage 21 until the plunger reaches a larger-diameter lower portion of cylinder 23.

The pipes 33, 34, are connected by a valvecontrolled resistance unit. This unit comprises a body part or casting 35 having inlet and outlet branches 36, 31, respectively connected to the pipes 33, 34. The body 36 contains an upwardlyopening one-way valve 39 for the quick return of iluid from the cylinder 8 to cylinder 4, and this valve is by-passed by a passage 39 communicating with the space above said valve 38 by an opening 40 .that is controlled by a spring-loaded valve 4I suitably guided in the wall of an extension part 42 of the body and having its end face subjected to lthe pressure of the iiuid proceeding from the ram cylinder. The spring 43 acting on the valve, and normally causing it to close the said opening 40, is contained within the extension part 42 which is suitably attached to the body 35 and has screw means 44 for adjusting the strength of the spring. The valve 4I opens to an extent which is in accordance with the pressure of the iluid upon its end face, and thus automatically varies the resistance to the flow of the uid so as to produce a substantially constant resistance to the movement of the ram.

The valve 38 can be raised from its seat and held in that position by means of a screwed rod 46 separate from said valve 38 but aligned with the stem thereof. A shut-oil valve 41 is fitted in a pipe connection 48 between pipe 34 and a uidcontaining vessel 49 on which the cylinder 8 is mounted, whilst a non-return valve is tted at 50 in the pipe 5I between the upper end of cylinder 4 and the said pipe connection 48. With this arrangement, by raising valve 38 and opening shut-off valve 41 the weight of the pressure plate I and ram 3 in the primary cylinder 4 is sulicient to discharge the iluid from said cylinder 4 into the vessel 49. This is necessary in order that tools may be set on large presses. The non-return valve at 50 prevents fluid from passing back into the cylinder 4 and above the ram 3 during this operation, but any fluid leaking upward-s past the ram 3 can be discharged through pipe 5I into the vessel 49.

Also, by very slightly raising the valve 38 with the stop valve 41 shut, lower pressures than are normally required for making pressings can be obtained, as according to the distance the valve 38 is raised, so more or less fluid is ,by-passed around the resistance valve 4l without having to pass through the restricted aperture 40.

We claim:

A hydraulic pressure-controlling appliance comprising a primary cylinder containing a hydraulic uid, a pressure-applying ram in said cylinder, a secondary cylinderconnected to the primary cylinder by a pipe line, a piston in the secondary cylinder, elastic means resisting movement of the piston, and a combined resistancevalve and quick-return valve unit in the pipe line, said unit consisting of a body having an inlet branch and an outlet branch and forwardow and return-110W passages between said branches, a spring-loaded resistance valve in said body controlling the ilow of fluid from. the primary to the secondary cylinder through the forward-110W passage in the body, being subjected to the ud pressure prevailing in the primary cylinder and operating to restrict said-flow to an extent that varies inversely with the said fluid pressure, a one-Way Valve controlling the returnflow passage in the body' and which opens only to permit the return ow of fluid from the secondary cylinder to the primary cylinder, and. an externally-operable axially movable rod for raising the one-way valve from its closed position and for holding it in such raised position.

ARTHUR CARTER. GEORGE SLADE.

REFERENCES CITED The following references are of record in the le of thisA patent:

UNITED STATES PATENTS 

